Gymnosperms - Pollination is said to be direct as the pollen are deposited directly on the exposed ovules  Angiosperms - Pollination is said to be indirect as the pollen are deposited on the stigma of the pistil.

Pollination by bees is called mellitophily.

A diploid embryosac is formed from megaspore mother cell without a regular meiotic division
Example:
Eupatorium, Aerva

The endosperm in gymnosperms is haploid because it is formed from the haploid megaspore. In angiosperm the endosperm is triploid, a product or triple fusion.

Dichogamy stamens and stigmas mature at different times (protandry, Protogyny) Herkogamy - Stamens and stigmas are arranged in such a way, self pollination become impossible.

Pollination carried out by beetle is called cantharophily.

A single cell from a rare and endangered plant can be grown into a an entire plant. So it is considered as the best method.

Individuals formed by asexual reproductive methods are morphologically and genetically identical and are called clones.

The stem of a parent plant is allowed to develop roots. After formation of roots, the rooted part is cut and separated and planted to grow into a new plant (eg) Ixora and Jasminum.

Sucker - chrysanthemum
Stolon - jasmine

Hofmeister described the structure of pollen tetrad

Reproduction is a biological process in which an organism give rise to offsprings. This helps to maintain continuity of its species.